Campaign 9 of the K2 Mission

K2's Campaign 9 (K2C9) will conduct a ∼3.4 deg2 survey toward the Galactic bulge from 7/April through 1/July of 2016 that will leverage the spatial separation between K2 and the Earth to facilitate measurement of the microlens parallax πE for ≳120 microlensing events, including several planetary in nature as well as many short-timescale microlensing events, which are potentially indicative of free-floating planets (FFPs). These satellite parallax measurements will in turn allow for the direct measurement of the masses of and distances to the lensing systems. In this white paper we provide an overview of the K2C9 space- and ground-based microlensing survey. Specifically, we detail the demographic questions that can be addressed by this program, including the frequency of FFPs and the Galactic distribution of exoplanets, the observational parameters of K2C9, and the array of ground-based resources dedicated to concurrent observations. Finally, we outline the avenues through which the larger community can become involved, and generally encourage participation in K2C9, which constitutes an important pathfinding mission and community exercise in anticipation of WFIRST.